This invention relates to the field of combination wrenches, and in particular to valve wrenches which fit on the hand wheel of a valve thereby increasing leverage and the mechanical advantage for an individual when opening and closing a valve.
Prior art combination wrench designs have been aimed at increasing the leverage and mechanical advantage in tightening or loosening nuts, bolts, or pipes. No combination wrench design has addressed the problem of rotating hand wheel operators to open and close valves.
The problem with prior art combination wrenches is that they cannot grasp the circular shaped hand wheel operator without having considerable looseness of the hand wheel rim relative to the wrench. It is common for valves to be difficult to open and close due to nonuse or poor accessibility. When these problems occur, a valve wrench must be used.
Examples of prior art devices include those disclosed in the following United States Patents:
U.S. Pat. No. 4,738,167 discloses an extending device for tools having a circular shape with the top covered with a small square configured central opening. The bottom of the cylindrical configuration has a cut out oval shaped channel running diametrically through the cylinder. The cylinder is placed upon the handle of a tool so that the channel contains the hand portion of the tool. A ratchet or other driver means is placed in the square shaped opening on the top of the cylinder. This arrangement then increases the leverage and mechanical advantage for an individual when trying to loosen or tighten nuts, bolts, or pipe. One problem with this device is that it cannot accept circular shaped objects due to the channels longitudinal design. Another problem with this device is that it requires other tools to function. Unlike a combination wrench of solid design, this device works in combination with other tools which creates an unstable arrangement when trying to increase leverage.
U.S. Pat. No 4,729,281 discloses a conventional wrench with an extension handle apparatus. The extension handle has a plurality of openings that align with an opening in the conventional wrench. A bolt is then inserted through both openings and secured so that the extension handle is locked in place. The leverage of the conventional wrench is then increased an amount proportional to the extension handle setting.
U.S. Pat. No. 4,596,167 discloses a wrench set having individual wrenches comprising a straight shank with one end a stud socket and the other a stud drive. Individual wrenches can be combined in a straight line to multiply leverage when tightening or loosening nuts and bolts.
U.S. Pat. No. 1,371,533 discloses a wrench extension handle. A conventional double-end fixed jaw wrench is used in combination with an extension handle to increase leverage when tightening or loosening nuts and bolts. The extension handle design is such that one end interlocks with either end of the double-ended fixed jaw wrench thereby eliminating the need for clamping devices to join the two together.
U.S. Pat. No. 960,691 discloses a pipe wrench that has been modified so that the handle end features a hammer, wire cutter and pincers
U.S. Pat. No. 383,049 discloses a pipe wrench that has been modified so that the handle end features a ratchet device to tighten or loosen nuts and bolts of varying sizes.